For RAC database one instance is
running and when I try to start the second instance I am getting following errors

[oracle@node1 script]$ sqlplus / as sysdba

SQL*Plus: Release 12.1.0.2.0 Production on Wed Jul 20 12:07:53
2016

Copyright (c) 1982, 2014, Oracle. All rights reserved.

Connected to an idle instance.

SQL> startup

ORACLE instance started.

Total System Global Area 3305111552 bytes

Fixed Size
2929744 bytes

Variable Size
3238005680 bytes

Database Buffers
50331648 bytes

Redo Buffers 13844480 bytes

ORA-01105: mount is
incompatible with mounts by other instances

ORA-19808: recovery
destination parameter mismatch

Solution Description

See below the value for the
db_recovery_file_dest_size is just 10. There is no G/M/K mentioned. That is the
reason for the error. There might be chances of mismatch in values on both
nodes. To fix this we have to make these values in sync.